The present invention relates to a non-impact printer and, more particularly to a electrographic printer having a developing unit employing a two-component toning system using toner and carrier particles.
The electrographic printer uses the mixture of toner particles and reusable carrier particles for forming the toner particles onto a photoconductor surface thereof. The toner particles that form images are positively or negatively charged, and are statically attracted to the carrier particles which have an opposite charge. The toner and carrier particles are mixed and contained in a container. During the development process, the toner particles are carried by the carrier so as to be wiped across the photoconductor surface. The carrier particles are returned to the container after the transport of the toner particles onto the photoconductor surface. In the developing process of the two-component toning system, it is important to maintain a proper toner-carrier mix in order to produce fine reproduction. During the development process, the carrier particles, however, adhere to the photoconductor surface in a situation in which the power supply to the developing unit is temporarily shut off due to a malfunction of the machine and as a consequence, the volume of carrier particles is reduced to less than the proper volume required to sufficiently carry the toner particles.
Therefore, it is an object of the present invention to maintain a proper toner-carrier mix, especially to prevent the carrier particles from adhering to the photoconductor surface, in order to produce fine reproduction.